1. Field of Invention
The present invention concerns an implant for osteosynthesis, for the immobilization and/or stabilization of tubular bones following fractures or osteotomies, especially of rib bones, comprising at least a first implant component that has a means of attachment for attaching the first implant component to a tubular bone in a region of the tubular bone close to the fracture or osteotomy. Furthermore, the invention concerns an implant system, comprising a set of geometrically differently shaped implant components, and uses of an implant or implant system.
2. Discussion of Related Art
When, for example in the thorax region, tubular bones are broken or osteotomy is performed, the thorax is stabilized as a basic principle, externally in the case of most fractures. This can lead, however, to imperfect repositioning of the bones. An exercise-stable state (to nonetheless facilitate breathing and certain mobility of the patient) or a function-stable state (and thus healing that is as complication-free as possible) is only attained after a long period of convalescence under conditions cumbersome for the patient.
If surgical intervention is carried out after a fracture, resorbable suture material, such as surgical wire or osteosynthesis wire, is used in practice for the purpose of immobilizing the bones. The same procedure is adopted with osteotomized (surgically separated) bones in the thoracic region that are indicated, for example, in the case of thorax deformities.
The goal is to attain a state of exercise stability or function stability as soon as possible. Exercise stability means that, after the operation, the patient must be able under guidance to exert a light load on the material through indication-specific exercises, without the material breaking, shifting or deforming. Function stability is when the implant material accommodates the full function load at least up to a certain degree of reossification of the broken or osteotomized area, without breaking or, for example, changing by bending in shape or position.
Three-dimensional exercise-stable or even function-stable osteosynthesis or stabilization of the thorax, however, is hardly possible with conventional materials (e.g. resorbable suture material or osteosynthesis wire). The suture material may be useful to a certain extent for osteosynthesis, but it has minimal intrinsic stability and is therefore of limited suitability for stabilization. Thus, neither an exercise-stable state is created in the short term nor a function-stable state is created in an acceptable period of time. The wire does not actually act as a stable bridging material. Due to the long duration of convalescence until complete regeneration (or at least until exercise stability of the thorax fracture is attained; this takes somewhere in the region of months), the patient is exposed to severe pain, high-grade mobility restrictions and various other inconveniences, such as long hospitalization. In addition, the wires made from steel (but not from implant steel) may break in certain circumstances and cause complications.
The consistency of the osseous areas in the thoracic region naturally differ in accordance with their functionality. The range extends from cartilaginous structures to solid, cortical bone. In thoracic surgery, it is assumed for this reason that reossification or complete healing of separated bones proceeds much more slowly than is the case for pure corticospongeous bones. Depending on many different factors, such as the age of the patient, the blood circulation through the area concerned, and the anatomically-related mechanical load on the area concerned, the time span can be expected to be twice that for corticospongeous bones (it is known from the literature that, in a young adult, full reossification of bone areas osteomotized and stabilized by suitable osteosynthesis material takes a year; however, just six weeks after a fracture or osteotomy, the bone concerned already has approximately ⅔rds of the stability of an intact bone).
Usually, surgical intervention and connection in the case of large tubular bones consist in attaching metal plates to the bone and fastening them by means of screws or nails. The nails, screws and plates usually consist of surgical steel or titanium.
Because of the soft tissue structures in the thoracic region, however, it is not usual, as is the case for large tubular bones, to employ osteosynthesis plates in connection with osteosynthesis screws for the purpose of an immobilizing stabilization since anatomically induced movements would prematurely loosen such an implant and thus loosen the immobilization, a fact which, post-surgery, leads under exercise and/or function load to premature loosening, misalignment or even breakage of the implant. In practice, therefore, immobilizing stabilization in the thoracic region by means of an implant is rather uncommon.
When an implant is used, immobilization merely consists in winding osteosynthesis wire or suture material around an implant section and around the bone. This method, however, is difficult to execute and can lead to ready detachment of the implant from the bone.
It would at any rate be desirable to effect better immobilization of the bones in the region of the fracture or osteotomy, to reposition them accurately and, for the sake of making breathing as free of complications as possible, to attain an exercise-stable state as quickly as possible and a function-stable state as soon as possible.
A further general problem of performing osteosynthesis can consist in the fact that patients respond allergically to implants made from implant steel. Implant steel has a high proportion, for example, of nickel or chrome that can trigger tissue reactions. In addition, these metals can lead to sensitization of the tissue long after an implantation, with the result that in extreme cases the material must be explanted again.